Diaphragm valves are generally known and include a valve arrangement wherein a diaphragm seals against an annular valve seat thereby prohibiting the flow of fluid through the valve. As such, the valve seat is used to seal off an inlet or outlet passageway by engaging with the diaphragm. Diaphragms may be made of metal or non-metal materials.
Typical valve seats used with metal diaphragms are designed from a plastic based material, such as polychloro-trifluoro-ethene (PCTFE) or polyimide. However, non-metal valve seats have properties that change when subjected to environmental factors outside the parameters of rated use, such as high or low temperature ranges or exposure to highly corrosive or chemically incompatible fluids. In such aggressive applications, metal valve seats have been used, however, the performance requirements of such known all-metal valves do not typically match the performance of plastic based valve seats. For example, a valve with a metal valve seat may demonstrates a higher leak rate, a decrease in the number of operable cycles, or an increase in the required actuation force. Decreasing the rated number of cycles is a disadvantage, and this disadvantage is even larger for systems operating at high temperatures or regulating a corrosive material as replacement costs can be high. This is because the valve is frequently used to control the flow rate of such materials, thus requiring a dramatic increase in the number of cycles required on a regular basis.